Conventionally, as apparatuses that can sense an image for recording and reproduction, a digital still camera and a digital video camera are known. So-called retouching is often performed on the image data acquired by such apparatuses, involving downloading the image data to a personal computer (PC) and editing and processing the image data on the PC.
As examples of such retouching, there is changing the size, color, brightness, shape, etc. of the image, or projecting the image onto a three-dimensional surface. Additionally, correction of lens bulge, arising at the image sensed by an image-sensing apparatus such as a digital still camera, is also one type of such image processing.
These types of processing are typically performed on a PC using image editing software. FIGS. 13A and 13B show examples of transforming an image using image editing software, with FIG. 13A showing an example of reducing the original image vertically and FIG. 13B showing an example of adding a special effect that twists the original image from the center.
However, when editing or processing the image, for example, transforming the size of the image, adding special effects, or the like, as described above with the conventional art, although the editing record during editing with the image editing software can remain in memory, the editing record cannot be known from the image data stored after editing is finished.
Therefore, when one wants to know the content of the editing carried out in the past from the image data after the image data is saved, one can only guess from the reproduced image itself.
At the same time, due to the impact of a bulge of the lens that cannot be completely eliminated in the lens design, an image sensed via an optical system experiences bulges called barrel-type and spool-type as shown in FIGS. 14A and 14B, respectively. In particular, it is known that bulge increases markedly when using a wide-angle lens. As a procedure for performing this type of image bulge correction of an image, Japanese Laid-Open Patent Publication (Kokai) No. 2000-125175 discloses a procedure involving attaching to the image correction bulge parameters calculated on the basis of characteristics of the image-sensing apparatus that sensed the image, using these parameters to carry out gross automatic correction, and thereafter fine-tuning the image manually while observing the image. As shown in FIG. 15, this fine-adjustment procedure involves correcting the image so that any visual bulge disappears by using utility poles or other such essentially straight vertical portions in the image as a reference.
However, when using a correction tool and manually correcting the image while observing the image, it is very difficult to make the proper adjustments if there are no vertical straight lines like those shown in the example in FIG. 15 included in the image that can be used as references.